From Selected Triazines

Following lifetime feeding studies at the prescribed treatment levels, veterinary pathologists examine approximately 50 tissues from each animal for the presence of tumors or other evidence of tissue damage. The results of such oncogenicity studies in mice, conducted with the selected triazine herbicides, are presented in Table 25.6. 

None of the selected triazines showed any evidence of inducing tumors in mice, despite high feeding levels doses ranged from 87 to 1140mg/kg/day and were equal to or exceeded the MTD. The chloro-.v-triazines (e.g., atrazine, cyanazine, propazine, and simazine) resulted in either an increased incidence or an earlier onset of mammary tumors when administered to female SD rats at high feeding levels, as presented in Table 25.7. 

A study was designed to define the relative rates of dealkylation of selected triazine herbicides and two monodealkylated triazine degradation products in the unsaturated zone and in surface runoff. Atrazine and propazine degrade to DEA by deethylation and deisopropylation, respectively. Similarly, atrazine and simazine can both dealkylate to DIA by removal of an isopropyl and ethyl side chain, respectively (Figure 30.12). Differences in the concentration of the dealkylated degradation product from the two different sources should indicate any preferential removal of ethyl versus isopropyl side chain. Furthermore, because monodealkylated DEA and DIA have different side chains remaining, their relative rate of removal should provide additional information on the liability of the ethyl side chain versus an isopropyl side chain. 

Ureides (e.g., diuron, linuron) and triazines (e.g., atrazine, simazine, ametryne) all act as inhibitors of photosynthesis and are applied to soil (see Figure 14.1 for structures). They are toxic to seedling weeds, which they can absorb from the soil. Some of them (e.g., simazine) have very low water solubility and, consequently, are persistent and relatively immobile in soil (see Chapter 4, Section 4.3, which also mentions the question of depth selection when these soil-acting herbicides are used for selective weed control). 

A plefhora of methods developed for the determination of triazine compounds in water, soil, crops, biological fluids, etc., have been reported in the literature, and several excellent reviews are available for the interested reader. " More method papers are published on the determination of triazines in water than for all other sample matrices combined (water > soil > crop). The majority of the water method reports relate to the determination of parent triazine compounds plus compounds from one or more other chemical classes of pesticides (e.g., phenoxy acids, carbamates, pheny-lureas, acetanilides, acetamides, organophosphorus compounds, etc.) for generalized multi-residue screening or monitoring purposes. Addressed in other more selective... 

Specifically for triazines in water, multi-residue methods incorporating SPE and LC/MS/MS will soon be available that are capable of measuring numerous parent compounds and all their relevant degradates (including the hydroxytriazines) in one analysis. Continued increases in liquid chromatography/atmospheric pressure ionization tandem mass spectrometry (LC/API-MS/MS) sensitivity will lead to methods requiring no aqueous sample preparation at all, and portions of water samples will be injected directly into the LC column. The use of SPE and GC or LC coupled with MS and MS/MS systems will also be applied routinely to the analysis of more complex sample matrices such as soil and crop and animal tissues. However, the analyte(s) must first be removed from the sample matrix, and additional research is needed to develop more efficient extraction procedures. Increased selectivity during extraction also simplifies the sample purification requirements prior to injection. Certainly, miniaturization of all aspects of the analysis (sample extraction, purification, and instrumentation) will continue, and some of this may involve SEE, subcritical and microwave extraction, sonication, others or even combinations of these techniques for the initial isolation of the analyte(s) from the bulk of the sample matrix. 

Analysis of pesticides in water was performed by fully automated online solid-phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS/ MS) [25, 31]. These pesticides (a total of 22 belonging to the classes of triazines, OP, chloroacetanilides, phenylureas, thiocarbamates, acid herbicides, and anilides) were selected on the basis of previously published studies [20, 25], information gathered from the water authorities, and known use in rice crops. 

A novel type of heterocyclisation reaction involving the dipolar cycloaddition of jV,A-dialkylamino substituted thioisomunchnones and azodicarboxylates giving 1,2,4-triazine derivatives has been reported. The cycloadduct 26 is initially formed from the isomunchnone 24 and the azodicarboxylate 25, it then undergoes a selective fragmentation to give the 1,2,4-triazine 27 <99TL8675>. 

In the case of quaternary derivatives made from the non-planar aliphatic amines 7.64, 7.65 and 7.66, steric strains further destabilise the C-N+ bond so that reaction with cellulose occurs under alkaline conditions at 30 °C, whereas temperatures of about 40-50 °C are required for the pyridinium derivatives 7.67. The quaternisation approach appeared to offer the opportunity to prepare dyes yielding reactivity levels intermediate between those of aminochloro- and dichlorotriazine dyes without loss of the desirable stability of the dye-fibre bond to acidic conditions that is characteristic of aminohalotriazine dyes. Unfortunately, this ideal was not attainable because of the objectionable odours of the tertiary amines liberated by the fixation reaction and the sensitivity of the reactivity behaviour of the quaternised derivatives to the nature of the chromogen attached to the triazine ring, making it difficult to select compatible combinations of dyes. 

SANEX 3 used the 2,6-Z) -(5,6-dialkyl-1,2,4-triazine-3-yl)pyridine family of extraetants eontaining the propyl group, whieh are able to selectively extract trivalent actinides from Imoldm EINO3 [53,78]. The extractant was 0.04mol dm in a mixture of 70%/30% TPH/octanol. A flow sheet based on this solvent has been tried and is shown schematically in Fig. 12.21 the results are given in Table 12.13. The feed was an... 

The isomeric l,2,4-triazin-5-ones also have herbicidal activity, and of these the 4-amino compounds stand out. Metribuzin (3) and metamitron (4) (68SAP6804409) possess excellent selectivity, the former being manufactured on a very large scale. Metribuzin can be synthesized from 3,3-dimethyl-2-oxobutyric acid (Scheme 3). 

---